Such air bubble sensors are known from practice and serve, for example in mobile heart-lung machines, to increase the safety of the patient from air embolism. As soon as air is detected in a blood conducting tube by such an air bubble sensor, safety clamps can be activated which prevent a further conducting of air bubbles into the patient's body.
In known air bubble sensors, a blood conducting tube is inserted into the holder, which can cost valuable time in an emergency. Air bubble sensors are furthermore known in which a coupling medium has to be introduced into the holder before the insertion of the tube to improve the coupling between the air bubble sensor and the tube. This is in particular likewise time-consuming and prone to error in emergencies.